Such a closure is already known from German utility model DE 299 16 436 U1. This generic closure serves to be placed onto a container into which the substance held in the container is to be filled. By moving the screw cap, the chamber wall executes an axial movement, so that a passage can be opened up through which the substance can flow into the container.
In this context, it is conceivable for the substance to be liquid, solid or pasty. In particular, with closures of this type, substances can be stored that are only to be brought into contact with these contents shortly before the consumption of the contents.
As soon as the screw cap or its chamber wall has opened up the passage, the substance can reach the inside of the container and can mix with its contents. The container can be shaken for this purpose.